DEVELOPMENT OF THE EGG OF CLAVA LEPTOSTYLA. 2 19 



dung rothlich erscheint, zeigt nacht derselben eine blaugraue 

 Fahrbung." This point is confirmed in the case of C. leptostyla, 

 in which essentially the same process takes place. 



Perhaps a few words may be added as to the significance of the 

 development of pigment in connection with these yolk granules. 

 I have in recent papers ('O4 1 , 'O4 2 ), submitted certain views as to 

 this subject and it may suffice in general to refer to those discus- 

 sions. In the former it was said that pigments in organisms 

 might appear under three aspects : (i) Those directly serviceable 

 to the organism, as in chlorophyll, haemoglobin, etc. ; (2) as 

 waste products, which embrace probably the more numerous of 

 organic pigments, such as guanin, melanin, etc. ; (3) as reserve 

 products, of which the lipochromes are typical. In all probability 

 the various pigmentary matters found in eggs belong to the third 

 of these classes. And here undoubtedly should be classed the 

 pigmentary granules of Clava, and other similar pigments of 

 hydroid ova. In the second paper attention was directed to a 

 special case, that of Pacliycordyle, already referred to, in which 

 one may trace the various stages in the growth of the egg and 

 the formation of the pigmentary bodies. Here as in Clava there 

 can hardly be reasonable doubt that the process is a gradual and 

 progressive anabolism, so far as the granules themselves are con- 

 cerned, but it must still be a somewhat open question as to the 

 exact relation of pigmentation thereto. May it not be probable 

 that here, as in many of the more active phases of metabolism in 

 which pigments are more or less evident expressions of excretory, 

 or waste products, the pigment itself, though associated with 

 anabolic activities, is an expression of the correlative process of 

 catabolism ? In other words, that even in those constructive 

 processes involved in the storage of reserve matters, whether as 

 proteids, fats, or whatever they be, there is involved the insep- 

 arable process of energy bestowed, and that as one of the signs 

 of such energy its imprint is left in these pigmentary elements ? 

 Such I am inclined to believe is what actually happens. And as 

 the nature of these processes differ more or less in various 

 organisms so the pigmentary signs of waste will likewise differ. 

 Hence the purple pigment of the eggs of Clava, the pinkish of 

 Pennaria, the reddish of Eudendrium, etc. 



